Supplemental Balance Sheet Information (Components of Prepaid Expenses and Other) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid taxes and tax refunds receivable	$ 111.6	$ 99.3
Receivables other than trade	67.2	68.3
Prepaid brochure costs, paper and other literature	64.8	73.2
Other	52.8	50.5
Prepaid expenses and other	$ 296.4	$ 291.3